No.2（1999）28.Dosimetry and sterility assurance in gamma irradiation facility

Masayuki SEKIGUCHI

The international standards for radiation sterilization, ISO 11137 and ISO/TR 13409, describe that medical device samples for dose setting experiments and sterilization dose auditings, shall be irradiated within narrow limits. Therefore, irradiation characteristics of irradiators and absorbed doses in products should be measured accurately by the dosimeter with the traceablility to national standards and known uncertainty. In this study, Ceric-Cerous dosimeters calibrated by NPL alanine dosimeters were mainly used to estimate the characteristics in our irradiator, and the differences of the dose response in production batches were evaluated to verify the reliability. The change of gamma source affected the vertical distribution of the dose rate, and the uniformity in horizontal distribution of dose rate in the new source was gradually decreased as the distance to the source was shortened. Based on these irradiation characteristics, how to fulfill the requirements for dosimetry or irradiation of samples under those standards was further examined.

Keywords
Radiation sterilization, Dosimetry, Gamma radiation, International sterilization standards, Dose distribution, Traceability

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